Reactant delivery for engine exhaust gas treatment

ABSTRACT

A reactant delivery system for engine exhaust gas treatment may include a tank in which a reactant is received, a pumping device, a pressure relief device, and a reactant distribution device. The pumping device may have an inlet disposed within the interior of the tank to receive the reactant, and an outlet through which the reactant is discharged. The pressure relief device may have an inlet in fluid communication with the outlet of the pumping device, a primary outlet to discharge the reactant under pressure to a downstream location, and a bypass outlet through which at least some of the reactant discharged from the pumping device is selectively discharged. And the reactant distribution device may be in fluid communication with the bypass outlet of the pressure relief device and have a plurality of outlets to distribute the reactant to at least two different locations within the tank.

REFERENCE TO CO-PENDING APPLICATIONS

This application is a divisional of U.S. application Ser. No. 12/608,408filed Oct. 29, 2009 and claims the benefit of U.S. ProvisionalApplication Ser. No. 61/170,422 filed Apr. 17, 2009 and U.S. ProvisionalApplication Ser. No. 61/110,383 filed Oct. 31, 2008.

TECHNICAL FIELD

The present disclosure relates generally to reactant delivery systemsand apparatus used for treatment of exhaust gas from combustion engines.

BACKGROUND

Selective catalytic reduction (SCR) systems are increasingly used toreduce nitrogen oxides present in exhaust gas from internal combustionengines and particularly diesel engines. SCR systems store an SCRreactant in a liquid or solid state. The SCR reactant typically includesa combination of urea —(NH₂)₂CO— and water. An exemplary SCR reactant isADBLUE, which is the registered trademark held by the German Associationof Automobile Industry for an aqueous urea solution. The SCR reactant isdelivered into a flow of exhaust gas downstream of an engine andupstream of one or more catalytic converters. A typical SCR systemincludes a selective discharge catalyst in an exhaust system, aninjector to provide doses of the SCR reactant to the downstreamcatalyst, and an SCR reactant delivery system.

The SCR reactant delivery system includes a tank defining a main volumefor the SCR reactant, and a reservoir structure disposed in the mainvolume of the tank and defining a cold start volume of the SCR reactant.Because the SCR reactant will freeze in some conditions, a volume of thefrozen SCR reactant inside the reservoir structure is heated so as tomelt the frozen SCR reactant to provide SCR for operating the engine incold weather conditions. Current United States' Federal Regulationsrequire the SCR reactant to be supplied to the exhaust flow withintwenty minutes of cold engine startup in cold weather conditions of atleast −40 degrees centigrade.

SUMMARY OF THE DISCLOSURE

A reactant delivery system for engine exhaust gas treatment may includea tank in which a reactant is received, a pumping device, a pressurerelief device, and a reactant distribution device. The pumping devicemay have an inlet disposed within the interior of the tank to receivethe reactant, and an outlet through which the reactant is discharged.The pressure relief device may have an inlet in fluid communication withthe outlet of the pumping device, a primary outlet to discharge thereactant under pressure to a downstream location, and a bypass outletthrough which at least some of the reactant discharged from the pumpingdevice is selectively discharged. And the reactant distribution devicemay be in fluid communication with the bypass outlet of the pressurerelief device and have a plurality of outlets to distribute the reactantto at least two different locations within the tank.

In at least one implementation, a reactant delivery module for areactant delivery system having a storage tank in which a supply ofreactant is maintained may include a mounting flange formed of athermally conductive material and having a sealing surface adapted to becoupled to the storage tank, a reactant delivery device carried by themounting flange and within the storage tank, and an electricalconnection coupled to the flange to provide electrical power whichincreases the temperature of the flange. When the flange is in contactwith frozen reactant within the storage tank, the increased temperatureof the flange helps to melt the frozen reactant.

In at least one implementation, a SCR reactant delivery system forengine exhaust gas treatment may include a tank, a motorized pumpingdevice having an inlet, an absorbent filter coupled to the inlet of thepumping device to absorb and filter SCR reactant for delivery to thepumping device, and a heater extending adjacent the pumping device andthe absorbent filter.

In at least one implementation, a motorized pumping device may include ahousing including an axially extending outer wall at least partiallydefining a housing interior, and a dividing wall to divide the housinginterior into a motor chamber wall on one side of the dividing wall anda pump chamber on the other side of the dividing wall. A motor may becarried in the motor chamber of the housing, and a first magnetic disccoupling member may be disposed in the motor chamber and structurallycoupled to the motor. A pump assembly may be carried in the pump chamberof the housing and include a pump assembly case including an outer wallin contact with the housing, a pump carried by the pump assembly caseand including a pump body defining a pump pocket, a pump port platedisposed against the pump body, a driven rotor disposed in the pumppocket between the pump port plate and the pump body, and a drive rotordisposed in the driven rotor between the pump body and the pump portplate. A second magnetic disc coupling member may be disposed in thepump chamber and operatively coupled to the first magnetic disc couplingmember through the dividing wall and structurally coupled to the driverotor through the pump port plate. A stationary shaft may be fixed tothe pump body and extend through the pump drive rotor, and may becoupled to the second magnetic disc coupling member to allow rotationthereof about the shaft.

In at least one implementation, a motorized pumping device may include ahousing including a motor chamber and a pump chamber, and a dividingwall between the motor chamber and the pump chamber. A motor may bedisposed in the motor chamber, and a first magnetic coupling member maybe disposed in the motor chamber on one side of the dividing wall andstructurally coupled to the motor. A pump assembly may be disposed inthe pump chamber and include a pump body and a drive rotor, a secondmagnetic coupling member disposed in the pump chamber on another side ofthe dividing wall and structurally coupled to the drive rotor andoperatively coupled to the first magnetic coupling member through thedividing wall, a center support disposed between the second magneticcoupling member and the pump body and including a hub carrying abearing, and a shaft coupled to the second magnetic coupling member,extending through the center support and bearing, and coupled to thedrive rotor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an exemplary form of an SCR reactantdelivery system that is used in treating exhaust gas from an internalcombustion engine;

FIG. 2 is a perspective view of the SCR reactant delivery system of FIG.1;

FIG. 3 is another perspective view of the SCR reactant delivery systemof FIG. 1;

FIG. 4A is a fragmentary view of an exemplary form of a heating elementfor use in the system of FIG. 1;

FIG. 4B is a fragmentary view with a portion broken away of an exemplaryform of a heating element for use in the system of FIG. 1;

FIG. 5A is a cross-sectional view of an exemplary form of a motorizedpumping device for use in the system of FIG. 1;

FIG. 5B is a cross-sectional view of another exemplary form of amotorized pumping device for use in the system of FIG. 1;

FIG. 5C is an enlarged cross-sectional view of a portion of themotorized pumping device of FIG. 5B;

FIG. 6A is a cross-sectional view of an additional exemplary form of amotorized pumping device for use in the system of FIG. 1;

FIG. 6B is a cross-sectional view of a further exemplary form of amotorized pumping device for use in the system of FIG. 1;

FIG. 7 is a cross-sectional view of a portion of an exemplary form of amotorized pumping device for use in the system of FIG. 1; and

FIG. 8 is a perspective view of an exemplary reactant delivery module;

FIG. 9 is another perspective view of the reactant delivery module ofFIG. 8; and

FIG. 10 is a fragmentary sectional view of a portion of a mountingflange of the module.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Exemplary SCR System

Referring in more detail to the drawings, FIG. 1 illustrates anexemplary internal combustion engine system 10 including an engine 12,an exhaust system 14 coupled in fluid communication to the engine 12,and a controller 16 to control the engine 12 and the exhaust system 14.The system 10 may also include an SCR reactant delivery system 18 whichmay be considered part of the exhaust system 14. Portions of thedelivery system 18 are also shown for general reference in FIGS. 2 and3. As will be described in greater detail herein below, the deliverysystem 18 is capable of thawing frozen solid SCR reactant into liquidform and delivering the liquid SCR reactant to another portion of theexhaust system 14.

The engine 12 converts chemical energy into mechanical energy bycombustion of air and fuel and may be of any suitable construction andcomposition. For example, the engine 12 may be a gasoline, diesel, orany other suitable type of engine that uses any appropriatethermodynamic cycle for combustion. The combustion yields a byproduct ofexhaust gas, which is delivered downstream of the engine 12 by anexhaust manifold 20 of the engine 12. The exhaust manifold 20 is coupledin any suitable manner to the exhaust system 14.

The exhaust system 14 is coupled to the exhaust manifold 20 to receivethe exhaust gases from the engine 12, treat the exhaust gases to removeor reduce pollutants, and convey the treated exhaust gases downstream tothe atmosphere. The exhaust system 14 includes a conduit 22 that may becoupled to the exhaust manifold 20 of the engine 12, and catalyticconverters 24, 26 in fluid communication with the conduit 22. Forexample, the catalytic converters may include an oxidation converter 24and a nitrous oxide converter 26. The oxidation converter 24 may includeany appropriate type of oxidation catalyst 28, and the nitrous oxideconverter 26 may include any suitable SCR catalyst 30 and anyappropriate NH₃ blocking catalyst 32.

The exhaust system 14 may also include various other devices to senseconditions or treat gases within the conduit 22. For example,temperature sensors 34 may be disposed upstream of the oxidationconverter 24 and downstream of the nitrous oxide converter 26. Inanother example, NOx sensors 36 may be placed upstream and downstream ofthe nitrous oxide converter 26. In a further example, an NH₃ sensor 38may be placed downstream of the nitrous oxide converter 26.

The exhaust system 14 also includes an SCR reactant injector 40 in fluidcommunication with the conduit 22 downstream of the oxidation converter24 and upstream of the nitrous oxide converter 26. The injector 40 maybe supplied with Liquid SCR reactant via the delivery system 18, whichmay include an SCR reactant line 42, which may be heated with anysuitable heating device 44. For example, the heating device 44 may be anelectrical resistance heating element, which may be coupled to andcontrolled by the controller 16.

The SCR reactant line 42 is coupled to a tank assembly 46, whichgenerally includes a tank 48 to contain the SCR reactant, a levelsensing device 50 to sense the level of SCR reactant contained in thetank 48, one or more temperature sensors 51 (one shown) to sensetemperature inside the tank 48, a pressurizing apparatus 52 topressurize the SCR reactant for delivery to the exhaust conduit 22, anda thawing apparatus 54 to thaw frozen SCR reactant to liquid form.

The tank 48 defines an internal volume for the SCR reactant and may beof any appropriate construction and composition. For example, the tank48 may have a lower wall 56 and an upper wall 58 and sidewalls 60therebetween to define the internal volume. The tank 48 may be composedof metal, plastic, or any other material suitable to contain the SCRreactant, which, for example, may include an SCR reactant such as a ureaand water mixture or solution.

The level sensing device 50 senses the level of SCR reactant in the tank48 and is coupled to the controller 16 to communicate the sensed SCRreactant level thereto, and may be of any suitable construction andcomposition. For example, the level sensing device 50 may include astator 62 and a floatable armature 65 movable along the stator 60 toindicate the level of SCR reactant. In another embodiment, the levelsensing device 50 may be a single point level sensor to indicate a lowlevel condition, and/or may be a continuous and motionless type of levelsensing device. The level sensing device 50 also or instead may includeother devices to measure solid or frozen SCR reactant such as radiofrequency sensors, thermistors, infrared sensors, or the like.

The temperature sensor 51 senses temperature of SCR reactant inside thetank 48 and the sensed temperature may be used as an input to thecontroller 16. For example, the controller 16 may use the sensedtemperature from the sensor 51 in switching between the primary heater96 and the secondary heaters 98. The sensor(s) 51 may be provided in anysuitable quantity and location in the tank 48.

The pressurizing apparatus 52 extracts liquid SCR reactant from insidethe tank 48, pressurizes the extracted liquid SCR reactant, anddischarges the pressurized liquid SCR reactant for delivery outside ofthe tank 48. The apparatus 52 may be of any appropriate construction andcomposition and, for example, the apparatus 52 may include a motorizedpumping device 64.

The motorized pumping device 64 may include a pump 66 to pressurize theliquid SCR reactant, a motor 68 coupled to the pump 66 to drive the pump66 via a magnetic coupling 70 across a dividing wall 72, an inlet 74through which liquid SCR reactant is extracted from the inside of thetank 48 into the pump 66, and an outlet 76 to discharge pressurizedliquid SCR reactant from the pump 66. The magnetic coupling 70 enablesuse of the dividing wall 72 to isolate the pump 66 from the motor 68 toprotect the motor 68 from the liquid SCR reactant. The magnetic coupling70 also permits the motor 68 to rotate even if the pump 66 is frozen andunmovable, for example, when the SCR reactant is frozen therein. Thepumping device 64 may be capable of any suitable output, for example,about 20 to 40 liters/hour at about 2.5 to 7.5 bar and, moreparticularly about 30 l/h and about 5 bar. The pumping device 64 may becarried by the tank 48 in any appropriate manner, for example, by theupper wall 58 via an adapter flange 78 that may be coupled to both thepumping device 64 and the upper wall 58 of the tank 48. The pumpingdevice 64 may be of any suitable design, for example, the exemplarydesigns described below with respect to FIGS. 5A through 7.

Also, the pressurizing apparatus 52 may include a sock or inlet filter80 to protect the system 18 by preventing at least some contaminantsfrom being extracted into the pump 66 and being delivered to thedownstream injector 40. The inlet filter 80 is coupled in fluidcommunication to the inlet 74 of the pump 66 in any appropriate manner,for example, by an inlet conduit 82, and may be of any suitableconstruction and composition. For example, the inlet filter 80 may becomposed of polyamide 6 or polyamide 6-6, polybutylene terephthalate, orthe like. In another example, the inlet filter 80 may include STRATAPOREfiltration media available from Cummins Filtration of Findlay, Ohio orNashville, Tenn. In any case, the inlet filter 80 may be constructed andcomposed in such a manner as to absorb, wick, or otherwise attract andhold SCR reactant therein, and may include a five to fifteen micronfiltering capability. Also, a sump temperature sensor 81 may be providedin proximity to the filter 80, for example, coupled in any suitablemanner adjacent the conduit 82. The sensor 81 may be any suitabletemperature switch with a desired setpoint.

Further, the pressurizing apparatus 52 may include a pressure reliefdevice 84 to allow pressurized liquid SCR reactant to bypass the SCRreactant line 42 and flow back to the internal volume of the tank 48when pressure in the SCR reactant line 42 is sufficiently high. Thepressure relief device 84 is disposed within the tank 48 and is coupledin fluid communication to the pump 66 in any appropriate manner, and maybe of any suitable construction and composition. The pressure reliefdevice 84 may have an inlet 86 in fluid communication with the outlet 76of the pumping device 64 via an outlet conduit 88 to receive pressurizedliquid SCR reactant therefrom, a primary outlet 90 to discharge theliquid SCR reactant under pressure to a downstream location outside ofthe tank 48, and a bypass outlet 92 to discharge excess liquid SCRreactant under pressure inside the tank 48. For example, the device 84may be a mechanical valving device including a valve 94 biased against avalve seat to a closed position and movable from its seat to an openposition at a predetermined pressure or threshold to allow liquid SCRreactant under pressure to be exhausted back into the tank 48 instead ofbeing discharged or delivered downstream to the SCR reactant line 42. Inanother embodiment, the pressure relief device 84 may also or insteadinclude an electromechanical valving device of any appropriate type incommunication with and controlled by the controller 16.

The SCR reactant thawing apparatus 54 thaws frozen SCR reactant in aselected volume within the internal volume of the tank 48. In otherwords, the apparatus 54 may selectively thaw frozen SCR reactantaccording to a given volume. The apparatus 54 may include a first heater96 as a primary source of heat, one or more secondary heaters 98, whichmay be carried on a secondary heater carrier 100 disposed at leastpartially around at least portions of the pumping device 64 and filter80, and a liquid SCR reactant distribution device 102 disposed in thetank 48 and coupled in fluid communication to the pressure relief device84.

The first heater 96 heats frozen SCR reactant in a specified volume ofthe tank 48. For example, the first heater 96 may extend in closeconforming relationship to the pumping device 64 and filter 80. Forinstance, the first heater 96 may extend in a longitudinal directionalongside or adjacent the level sensing device 50 and/or the pumpingdevice 64 over a substantial portion of the lengths thereof, forexample, over 50% of the lengths. The first heater 96 may also extend ina transverse direction alongside or adjacent a bottom portion of thepump 66, in a longitudinal direction alongside or adjacent the inletconduit 82, and in a transverse direction alongside or adjacent an uppersurface of the inlet filter 80. The first heater 96 is placed in suchproximity to the filter 80 that heat flux from the heater 96 thaws to aliquid frozen SCR reactant in and/or adjacent the filter 80. Statedanother way, the first heater 96 is placed close enough to the filter 80to saturate the filter 80 with heat. The proximity of the heater 96 tothe filter 80 is such that the heater 96 will not damage the filter 80and for good heat flux to maximize melting of the SCR reactant in thevicinity. Also, the heater 96 may be equipped with thermaloverprotection functionality to prevent damage to the filter 80 if theheater 96 is inadvertently supplied with excessive voltage, for example,full battery voltage at 12 Volts. The primary heater 96 may contact thefilter 80 without damage thereto because of inherent temperature setpoint(s) of the heater 96. The filter material is rated for over 80degrees centigrade and the heater 96 will self-regulate to shut off viathe setpoint(s) at 50 degrees centigrade. The first heater 96 may becoupled to the controller 16 and may be an electrical resistance heatingelement of any suitable construction and composition. For example, theheater 96 may include one or more positive temperature coefficient (PTC)heating elements.

The secondary heater(s) 98 heat frozen SCR reactant in a generalizedvolume of the tank 48 in contrast to the first heater 96. The secondaryheater(s) 98 may be coupled to the controller 16 and also may includeelectrical resistance heating elements of any appropriate quantity,construction, and materials. For example, and referring to FIGS. 4A and4B, the secondary heaters 98 may include PTC elements 104 encapsulatedin a phase-change material 106 (partially shown) and disposed within ahousing 108. In one example, the housing 108 can be injection moldedaround the phase-change material 106 and PTC elements 104. The secondaryheaters 98 may include one or more electrical leads 110 of any kind thatmay extend through the phase change material 106 and out of the housing108, which may be molded around the lead(s) 110. The secondary heaters98 may be of any suitable shape, for example, shark-tooth-shaped, andmay be of any suitable size.

The secondary heater carrier 100 supports the secondary heaters 98 andallows substantially unrestricted flow around the inside of the tank 48,and may be of any appropriate construction and composition. For example,the carrier 100 may be a generally self-supporting or rigid cylindricalmesh structure composed of conductive and/or insulative material, forexample, stainless steel, ceramic, or the like. The secondary heaters 98may be carried on or coupled to the carrier 100 in any suitable manner,for example, via fastening, molding, adhering, or the like.

The liquid SCR reactant distribution device 102 selectively distributesoverflow or bypass liquid SCR reactant from the pressure relief device84 over a selected area or volume within the tank 48. For example, thedevice 102 may distribute bypass liquid SCR reactant between thespecified and generalized volumes heated by the heaters 96, 98, and maybe of any appropriate construction and composition. For instance, thedevice 102 may include a conduit 112 coupled in fluid communication tothe bypass outlet 92 of the pressure relief device 84 and having aplurality of outlets 114 in various orientations to selectivelydistribute the bypass liquid SCR reactant within the tank 48.

The conduit 112 may be a flexible hose or a self-supporting or rigidtube or pipe and may be composed of any suitable material. The conduit112 may be of any suitable shape and size, for example, loop-shaped,ring-shaped, helically-shaped, or the like at least within the confinesof the carrier 100. In one or more implementations, the conduit 112 maybe arranged in a non-linear and/or non-planar fashion within the tank,or it may be provided in a linear or substantially linear fashion. Theoutlets 114 may be orifices or apertures provided along the length ofthe conduit 112 and may be provided in any appropriate size, shape, andquantity to collectively present little to no backpressure to thepressure relief device 84 so that it does not substantially change adesired or predetermined pressure setpoint of the pressure relief device84.

The apertures 114 may be positioned and directed so as to selectivelydistribute liquid SCR reactant in three planes or three dimensionalspace within the tank 48 in the vicinity of the filter 80 and pump 66.More specifically, for a given length of conduit 112, the total flowarea through the apertures 114 may increase with distance from thepressure relief device 84 to achieve relatively consistent flow and/orpressure delivered by the conduit 112. This may be accomplished, forexample, by increasing the size and/or quantity of the apertures 114 asthe distance from the pressure relief device 84 increases. Also, atleast some of the outlets 114 may be sized and located so as to directliquid SCR reactant onto the filter 80, for example, to decontaminatethe filter 80. The conduit 112 and its outlets 114 may be sized,oriented, and provided in a quantity to maximize distribution of liquidSCR reactant within the tank 48. The liquid SCR reactant distributiondevice 102 may also provide continuous and homogeneous flow of theliquid SCR reactant in the tank 48, for example, to promote miscibilityor solubility of the mixture or solution.

In general, the controller 16 may receive and process input from thevarious system devices in light of stored instructions and/or data, andtransmit output signals to the same and/or other system devices. Thecontroller 16 may include, for example, an electrical circuit, anelectronic circuit or chip, and/or a computing device. In the computingdevice embodiment, the controller 16 generally may include a processor116, memory 118 that may be coupled to the processor 116, and one ormore interfaces 120 coupling the processor 116 specifically and/or thecontroller 16 in general to one or more of the other system devices.Although not shown, the controller 16 and the other electrically poweredsystem devices may be supplied with electricity by a power supply (notshown), for example, one or more batteries, fuel cells, or the like.

The processor 16 may execute instructions that provide at least some ofthe functionality for the system 10. As used herein, the terminstructions may include, for example, control logic, computer softwareand/or firmware, programmable instructions, or other suitableinstructions. The processor 16 may include, for example, one or moremicroprocessors, microcontrollers, application specific integratedcircuits, and/or any other suitable type of processing device.

Also, the memory 118 may be configured to provide storage for datareceived by or loaded to the controller 16, and/or forprocessor-executable instructions. The data and/or instructions may bestored, for example, as look-up tables, formulas, algorithms, maps,models, and/or any other suitable format. The memory 118 may include,for example, RAM, ROM, EPROM, and/or any other suitable type of storagedevice.

Finally, the interface(s) 120 may include, for example, analog/digitalor digital/analog converters, signal conditioners, amplifiers, filters,other electronic devices or software modules, and/or any other suitableinterfaces. The interface(s) 120 may conform to, for example, RS-232,parallel, small computer system interface, universal serial bus, CAN,MOST, LIN, FlexRay, and/or any other suitable protocol(s). Theinterface(s) 120 may include circuits, software, firmware, or any otherdevice to assist or enable the controller 16 in communicating with theother system devices.

In operation, the engine 12 may be shut down from a warm or hotoperating condition in which liquid SCR reactant has already beenflowing from the tank 48 to the injector 40 for some period of time.Upon engine shut down, the SCR reactant line 42 typically may beevacuated. For example, the pumping device 64 may be operated in reversewherein the pump inlet and outlet are reversible. Accordingly, liquidSCR reactant is pulled through the SCR reactant line 42 from theinjector 40 and into the tank 48 via the pump 66 and filter 80. Morespecifically, the controller 16 may reverse direction of rotation of themotor 68 of the pumping device 64 to draw liquid SCR reactant throughthe SCR reactant line 42, and may open the injector 40 simultaneously orshortly thereafter to allow the liquid SCR reactant to be evacuated.Accordingly, shortly after engine shutdown little to no liquid SCRreactant remains in the fluid path between the injector 40 and the pumpinlet 74.

For engine startup in freezing weather conditions, the SCR reactantinside the tank 48 is frozen and cannot be immediately delivered to theexhaust conduit 22. However, within minutes the primary and/or secondaryheaters 96, 98 will thaw the SCR reactant to a liquid in the vicinity ofthe inlet filter 80, inlet conduit 82 and pump 66, and the inlet filter80 wicks more and more SCR reactant away from the frozen SCR reactantsurrounding the filter 80, and the SCR reactant line heater 44 preheatsthe SCR reactant line 42. Current vehicle requirements mandate that thesystem must be fully functioning and able to deliver the SCR reactantcontinuously without interruption within 20 minutes from engine startupat −40 degrees centigrade. It is anticipated that one or more aspects ofthe present arrangement enables this vehicle requirement to at least becomplied with, if not significantly exceeded.

In one embodiment, the secondary heaters 98 may be cycled on and offand/or operated according to zones. For example, the controller 16 maycycle all of the secondary heaters 98 in an on/off manner according toany suitable time, duration, duty cycle, or the like, which may bedetermined in response to, for example, one or more temperature readingsfrom one or more of the temperature sensors 51. In another example,secondary heaters 98 may be defined in zones which include less than allof the heaters 98. For instance, a general zone may include a volumeencompassed by the secondary heaters 98 but outside of a volume thatreceives full heat flux of the primary heater 96. Also, the general zonemay be divided into a plurality of specific zones based on the heat fluxproduced by the secondary heaters 98 and the heat distribution of theSCR reactant distribution device 102. Those of ordinary skill in the artwill appreciate that the quantity, size, and location of the zones maybe application specific and may be determined using any suitablecomputer modeling and/or empirical testing for each specificapplication.

In one exemplary embodiment, the primary heater 96 is energized to meltthe frozen solid SCR reactant into liquid SCR reactant for inlet intothe pump 66 and until the output of the pump 66 supplies liquid SCRreactant to the distribution device 102 with at least a minimallyacceptable amount of liquid SCR reactant flow that may be determined inany suitable manner.

The controller 16 may decrease the power supplied to the primary heater96, and may energize or increase power delivered to one or more of thesecondary heaters 98. One or both of the temperature sensors 51, 81 maybe used as inputs to the controller 16 for controlling operation of theheaters 96, 98. For example, the primary heater 96 may be fullyenergized to thaw the frozen SCR reactant and may remain fully energizeduntil the temperature switch 81 is tripped by an increase in temperaturebeyond its setpoint. At that point, the power supplied to the primaryheater 96 power will start to be decreased at some desired rate andpower supplied to the secondary heaters 98 will start to be increased.The full temperature range sensor 51 may then be used as input to thecontroller 16 to control the secondary heaters 98 as power to theprimary heater 96 eventually decays to zero and full power is applied tothe secondary heaters 98. When temperature readings from the temperaturesensor 51 outside of the virtual sump area reach a predetermined level,the controller 16 will then decrease power supplied to the secondaryheaters 98 to zero, for example, when the frozen SCR reactant is fullymelted.

In a similar example, the power decreased from the primary heater 96 maybe generally equal to the power increased to the secondary heaters 98.In another example, the primary heater 96 may be progressivelydeenergized as more and more of the secondary heaters 98 areprogressively energized. One or both of the heaters 96, 98 may beenergized until all of the SCR reactant in the tank 48 is in liquid formand reaches a desired temperature level.

One or more of the secondary heaters 98 may be energized at least untilthe phase change temperature of those secondary heaters 98 is reached.Thereafter, the one or more secondary heaters 98 may be deenergized andone or more others of the secondary heaters 98 may be energized at leastuntil the phase change temperature of those other secondary heaters 98is reached. This process may be repeated until all of the secondaryheaters 98 have been fully energized at least once, and the process maycontinue to heat some or all of the secondary heaters 98 in any suitablemanner. For example, the controller 16 may cycle the secondary heaters98 of the various defined zones in any appropriate manner so as toreduce maximum current draw to comply with various vehicle requirementsor for any other purpose. In one example, the secondary heaters 98 maybe cycled on for one minute and off for five to six minutes. Theselective cycling of the secondary heaters 98 may further enableefficient thawing of the frozen SCR reactant.

Also, once the phase-change material 106 changes phase from a solid to aliquid from heating by the PTC element 104, the phase-change material inits liquid state retains heat after the PTC element 104 is deactivatedand dissipates this heat more slowly than would the PTC element 104acting alone. Therefore, the secondary heaters 98 provide a certainamount of thermal mass and momentum wherein they retain sufficient heatto remain at a temperature above freezing for a substantial period oftime after being deenergized, for example on the order of about five tosix minutes.

The controller 16 determines when the pumping device 64 can startoperating in a suitable fashion without damage, cavitation, or the like.For example, within about six minutes from a −40 degrees centigradecondition, the pumping device 64 may start operating. Accordingly, thepump 66 may receive, pressurize, and discharge liquid SCR reactant tothe emptied fluid path between the pump inlet 74 and the injector 40. Atthat time, the controller 16 may open the injector 40 to start SCRexhaust gas treatment, may maintain the injector 40 closed, or may cyclethe injector 40 on and off according to any suitable duty cycle.

In any case, at least some liquid SCR reactant may be bypassed throughthe pressure relief device 84 and through the liquid SCR reactantdistribution device 102. Therefore, relatively warm liquid SCR reactantis selectively distributed over the cold frozen SCR reactant in the tank48 to accelerate thawing of the frozen SCR reactant and supplement andexpedite the thawing effort of the heaters 96, 98. Thus, less power maybe consumed to operate the heaters 96, 98 to thaw the frozen SCRreactant in the tank 48. In one example, the SCR reactant flowingthrough the SCR reactant distribution device 102 may reduce the time ittakes for the system 18 to be up to 100% operating capacity.

A virtual sump may be defined by one or more of the first heater 96, thesecondary heaters 98, the SCR reactant distribution device 102, and/orthe absorbent inlet filter 80 to thaw a cold start volume of SCRreactant. As the frozen SCR reactant is melted by the primary heater 96and the distribution device 102, liquid SCR reactant will be surroundedby frozen SCR reactant, thereby defining a liquid pocket of the SCRreactant in an ever increasing ice sump until all the frozen SCRreactant is melted. Accordingly, although a separate heated reservoirtank also could be used to thaw a cold start volume of SCR reactantdefined by walls, such additional structure may be rendered unnecessaryby the virtual sump.

Exemplary Pumping Devices

The motorized pumping device 64 of FIGS. 1-3 may include, for example,one or more of several exemplary devices of FIGS. 5A through 7. Forexample, and referring first to FIG. 5A, a motorized pumping device 264includes a housing 201 that may be coupled directly to a tank wall (notshown) for example at an opening thereof, a pump assembly 203 carried inthe housing 201 to extract, pressurize, and discharge liquid SCRreactant from the pumping device 264, and a motor 205 carried in thehousing 201 to drive the pump assembly 203.

The housing 201 provides support for the pump assembly 203 and the motor205, and may be of any appropriate construction and composition. Forexample, the housing 201 may include an outer wall 207 that may begenerally cylindrical and may include a shoulder 204 that locates alower end of the motor 205. The housing 201 may also include a mountingflange 209 that may extend generally transversely outwardly from theouter wall 207, and a dividing wall 211 that may extend generallytransversely inwardly from the outer 207 wall to divide the interior ofthe housing 201 into a motor chamber 213 at least partially defined by amotor chamber wall 207 a to support the motor 205 and a pump chamber 215at least partially defined by a pump chamber wall 207 b to support thepump assembly 203. The housing 201, or at least the dividing wall 211,may be composed of a nonmagnetic material. For example, the housing 201may be composed of any suitable polymeric material, for example,polyamide or NYLON 6/6, or a stainless steel material that issufficiently non-magnetic, for example austenitic or nickel containingstainless steel.

The pump assembly 203 may include a port housing or cover 217 includingan inlet 219 and an outlet 221, and a pump 266 that may be of anyappropriate type, for example, a turbine pump or a positive displacementpump such as a gear-rotor (or gerotor) type pump. The pump 266 mayinclude a pump body 223 having a hub 225 and defining a rotor pocket227, an inner or drive gear or rotor 229 disposed about the hub 225, andan outer or driven gear or ring or rotor 231 disposed in the rotorpocket 227. The drive rotor 229 and driven rotor 231 have meshed teethwhich provide pumping chambers as they rotate. The drive rotor 229 isdisposed at a lower end of the pump body 223 opposite of the centersupport 237. The pump assembly 203 may also include a drive coupling 233coupled to the rotor 229, a shaft 235 coupled to the drive coupling 233,a center support 237 and a bearing 239 carried by the center support 237to support the shaft 235 extending therethrough, and a driven member 241of a magnetic disc coupling 243 coupled to the shaft 235. The pumpassembly 203 may further include a case 245 that may be crimped over oneend of the center support 237 and over another end of the cover 217 witha seal 247 therebetween.

The cover 217 supports the pump body 223 and rotors 229, 231 and definesan inlet and outlet path thereto and therefrom, and may be of anysuitable construction and composition. For example, the cover 217 may beinjection molded from polyphenylene sulfide (PPS) or compression moldedfrom phenolic resin to include the barbed inlet 219 and barbed outlet221. The cover 217 may include a flat face to cooperate with a rotor endof the stationary pump body 223 and with the rotating rotors 229, 231,and a pocket in the flat face to accommodate the drive coupling 233.

The cover 217, pump body 223, and rotors 229, 231 at least partiallydefine an exemplary pump to pressurize the liquid SCR reactant, and maybe of any appropriate construction and composition. For example, thecomponents 223, 229, 231 may be formed from powdered or sintered metal,or the like. An inner diameter of the drive rotor 229 is piloted forrotation on the hub 225 of the body 223, and an outer diameter of thedriven rotor 231 is supported for rotation within the rotor pocket 227of the body 223. The pump body 223 may include a stepped outer surfaceto pilot the center support 237.

The drive coupling 233 couples the shaft 235 to the drive rotor 229, andmay be of any suitable construction and composition, for example,machined steel. The drive coupling 233 may include drive dogs 249, forexample, pins, that may be separate or integral and extend intocorresponding recesses or bores in the drive rotor 229, and an innerdiameter that may be coupled to the shaft 235 via corresponding flats,splines, or the like.

The shaft 235 couples the magnetic coupling 243 to the pump drive rotor229, and may be of any appropriate construction and composition, forexample, machined steel. The shaft 235 may include a pump end coupled tothe drive coupling 233, for example, via spline connection, press fit,or the like. The shaft 235 also may include a shoulder to axially locatea thrust bearing member 251, which is carried by the shaft 235 toaxially support the shaft 235 and protect the pump against axial forceson the shaft 235 induced by the magnetic attractive forces on the drivenmember 241. The thrust bearing member 251 may be a ring, clip, washer,or the like and may be composed of stainless steel. The shaft 235 alsoincludes one or more bearing diameters supported by the hub 225 of thepump body 223 and/or the bearing 239 of the center support 237, and acoupling end that may be coupled in any suitable manner to the magneticdriven member 241, for example by a set screw (not shown), a splineconnection, or the like.

The center support 237 provides axial support for the pump body 223 andradial support for the shaft 235, and may be of any appropriateconstruction and composition. For example, the center support 237 may beplastic, for example, a phenolic resin of any suitable type. The centersupport 237 may include an outer wall 253 that may be generallycylindrical and piloted to the stepped outer surface of the pump body223, and a wall 255 extending generally transversely from the outer wall253 and including a hub 257 defining a bearing pocket to accept thebearing 239 therein. The bearing 239 may be a bushing, which may becomposed of carbon, a roller bearing, which may be composed of stainlesssteel, needle bearing, or any other suitable device to support therotating shaft.

The driven member 241 of the magnetic coupling 243 responds to rotationof a drive member 259 of the magnetic coupling 243, and may be of anyappropriate construction and composition. For example, the magneticcoupling members 241, 259 each may be one half of the magnetic disccoupling 243. The coupling members 241, 259 may be constructed andcomposed of one or more rare-earth magnets hermetically sealed in astainless steel housing, or overmolded with phenolic or polyphenylenesulfide (PPS) resin. The magnets may be composed, for example, ofneodymium, iron, and boron (Nd₂Fe₁₄B). In another example, the couplingmembers 241, 259 may be commercially available from MagneticTechnologies, Ltd. of Oxford, Mass. An exemplary coupling is an MTD-0.2ASSY having 0.2 Nm of slip torque and constructed with an aluminum coverand six magnets. Accordingly, the driven member 241 may be the same orsimilar to the drive member 259, which is coupled to the motor 205 inany suitable manner.

The motor 205 provides an exemplary prime mover to drive the pump driverotor 229 and, thus, the driven rotor 231, and may be of any appropriateconstruction and composition. For example, the motor 205 may provideabout 30 m-Nm of torque at 13 Volts and 1.6 Amps at about 4,500 RPM, andmay be an HC series motor available from Johnson Electric IndustrialManufactory Ltd., of Hong Kong. The motor 205 includes an output shaft261 that may be coupled in any suitable manner to the magnetic drivemember 259, for example by a set screw (not shown), a spline connection,or the like.

In operation, the motor 205 is energized with electrical power so as torotate its drive shaft 261. Because of the mechanical connectiontherebetween, rotation of the shaft 261 causes the drive member 259 ofthe magnetic coupling 243 to rotate. Because of the magnetic attractiontherebetween, and through the dividing wall 211, rotation of themagnetic drive member 259 causes the driven member 241 to rotate.Because of the mechanical connection therebetween, rotation of thedriven member 241 causes the shaft 235 to rotate, thereby causing thedrive rotor 229 and driven rotor 231 to rotate by way of the drivecoupling 233 mechanically connected therebetween. Accordingly, operationof the motor 205 causes operation of the pump 266 through the wall 211disposed therebetween.

The wall 211 isolates the motor chamber from the pump chamber so thatcorrosive liquid SCR reactant from the pump chamber cannot enter themotor chamber. The magnetic coupling 243 permits the energized motordrive shaft to rotate even when the pump shaft does not rotate, forexample, when frozen SCR reactant is in the pump, thereby avoidingdamage to both the motor and the pump.

FIGS. 5B and 5C, illustrate another exemplary form of a motorizedpumping device 364 that is similar in many respects to the form of FIG.5A and like numerals between the forms generally designate like orcorresponding elements throughout the several views of the drawingfigures. Accordingly, the descriptions of the pumping devices 264, 364are incorporated by reference into one another in their entireties.Additionally, the description of the common subject matter generally maynot be repeated here.

The motorized pumping device 364 includes a housing 301 that may becoupled directly to a tank wall (not shown) for example at an openingthereof, a pump assembly 303 carried in the housing 301 to extract,pressurize, and discharge liquid SCR reactant from the pumping device364, and an electric motor 305 carried in the housing 301 to drive thepump assembly 303.

The housing 301 includes an outer wall 307 including a shoulder 304 thatlocates a lower end of the motor 305, a dividing wall 311 extendinginwardly from the outer wall 307, a flange 309 extending in generallytransverse direction from the outer wall 307, and one or more barbs 308therebetween. The barbs 308 enable insertion of the housing 301 into anaperture in a tank wall (not shown) until the flange 309 abuts the tankwall and thereafter the barbs 308 resist removal of the housing 301 fromthe tank wall.

The pump assembly 303 may include a pump body 317 including an inlet 319and an outlet 321 and defining a rotor pocket 327, and a pump 366. Thepump 366 may include a pump port plate 323, which may define one or morepump ports 324 and may be disposed against the body 317. The pump 366may also include a driven rotor 331 disposed in the rotor pocket 327 anda drive rotor 329 disposed in the driven rotor 331, both of which may besandwiched between the body 317 and the port plate 323. The drive rotor329 may also be supported on a stationary shaft 335, which may be fixedto the body 317 in a corresponding pocket or blind bore in the body 317at one end and may be coupled to a driven member 341 of a magneticcoupling 343 at another end.

The driven member 341 may be rotatably received on the shaft 335 andretained, for example, by a thrust washer 342 and a clip 344. The clip344 is engaged to the shaft 335 in any appropriate manner, for example,by being disposed in corresponding groove thereof. The thrust washer 342may be disposed in a pocket in a housing portion 340 of the drivenmember 341 and between the clip 344 and a shoulder of the housingportion 340 of the driven member 341. The thrust washer 342 may axiallyrestrain the driven member 341 to avoid interference between the drivenmember 341 and the dividing wall 311 of the housing 301 or a case 345.The thrust washer 342 and clip 344 may be composed of stainless steel.The driven member 341 may include an integral drive coupling 333, whichmay include one or more drive dogs 349 may slip fit into one or morecorresponding pockets or blind holes 349′ in the drive rotor 329. Theintegral drive coupling 333 may be loosely fit for rotation within aninner diameter of the plate 323.

The pump assembly 303 may further include the case 345, which may bemachined or drawn from stainless steel and may be crimped at one endwith clearance over the driven coupling 341 for a loose fittherebetween, and crimped at another end over the body 317 with aninterference or tight fit therebetween. The case 345 tightly conforms tothe body 317 and plate 323 in close contact therewith. In contrast, thecase 345 loosely corresponds to the driven coupling 341 to permit thedriven coupling 341 to freely rotate without interference from the case345. The distance between the crimp relative to a shoulder in the case345 may be set such that there is at least a slight axial gap betweenthe driven coupling 341 and the port plate 323 to avoid interferencetherebetween.

The motor 305 includes an output shaft 361 that may be coupled in anysuitable manner to a magnetic drive member 359 of the magnetic coupling343, for example by press fit, and/or by a washer 360 and a clip 362.The clip 362 is engaged to the shaft 361 in any appropriate manner, forexample, by being disposed in a corresponding groove thereof. The washer360 may be disposed in a pocket in a housing portion 358 of the drivemember 359 and between the clip 362 and a shoulder of the housingportion 358 of the drive member 359. The washer 360 may axially restrainthe drive member 359 to avoid contact between the drive member 359 andthe dividing wall 311 of the housing 301.

In operation, the motor 305 is energized with electrical power so as torotate the shaft 361. Because of the mechanical connection therebetween,rotation of the shaft 361 causes the drive member 359 of the magneticcoupling 343 to rotate. Because of the magnetic attraction therebetween,rotation of the magnetic drive member 359 causes the driven member 341to rotate about the stationary shaft 335 and within the case 345.Because of the mechanical connection therebetween, rotation of thedriven member 341 causes the drive rotor 329 to rotate. Accordingly,operation of the motor 305 causes operation of the pump 366 through thewall 311 disposed therebetween.

FIG. 6A illustrates another exemplary form of a motorized pumping device464 that is similar in many respects to the form of FIGS. 5A-5C and likenumerals between the forms generally designate like or correspondingelements throughout the several views of the drawing figures.Accordingly, the descriptions of the pumping devices 264, 364, 464 areincorporated by reference into one another in their entireties.Additionally, the description of the common subject matter generally maynot be repeated here.

The pumping device 464 includes a housing 401, an electric motor 405carried in the housing 401, and a pump assembly 403 carried in thehousing 401. The housing 401 may be machined or formed from metal in anyappropriate manner, for example, by rolling, flow forming, or the like.The housing 401 may be composed of a zinc-plated stainless steel,galvanized steel, or any other suitable metal.

The housing 401 may be of generally cylindrical shape and may include amotor section defining a motor chamber 413, a pump section defining apump chamber 415, and an external step or shoulder 414 therebetween. Themotor section of the housing 401 may include a crimped end 406 that iscrimped around an upper end of the motor 405, and a thickened wallportion 407 having a shoulder 404 that locates a lower end of the motor405. The pump section of the housing 401 may include a crimped end 408that is crimped around a lower end of the pump assembly 403.

The pump assembly 403 includes a case 445 with an outer wall 410 and adividing wall 411 extending transversely inwardly from the outer wall410 at an upper end of the pump assembly 403. The pump assembly 403 maybe disposed in the pump chamber 415 of the housing 401 so that thedividing wall 411 axially locates against the shoulder 414.

FIG. 6B illustrates another exemplary form of a motorized pumping device564 that is similar in many respects to the form of FIGS. 5A through 6Aand like numerals between the forms generally designate like orcorresponding elements throughout the several views of the drawingfigures. Accordingly, the descriptions of the pumping devices 264, 364,464, 564 are incorporated by reference into one another in theirentireties. Additionally, the description of the common subject mattergenerally may not be repeated here.

The pumping device 564 includes a housing 501, a motor 505 carried inthe housing 501, and a pump assembly 503 carried in the housing 501. Thehousing 501 may include an outer wall 507 defining a motor sectionincluding a crimped end 506 that is crimped around an upper end of themotor 505 and a shoulder 504 that locates a lower end of the motor 505,and also defining a pump section that may include a crimped end 508 thatis crimped around a lower end of the pump assembly 503.

The pump assembly 503 includes a case 545 that includes an outer wall510 and a dividing wall 511 extending transversely inwardly from theouter wall 510 at an upper end of the pump assembly 503. The dividingwall 511 may divide the interior of the housing 501 into a motor chamberin which the motor 505 and drive member 359 is disposed, and a pumpchamber in which the rest of the pump assembly 503 is disposed.

FIG. 7 illustrates another exemplary form of a pump assembly 603 that issimilar in many respects to the forms of FIGS. 5A through 6B and likenumerals between the forms generally designate like or correspondingelements throughout the several views of the drawing figures.Accordingly, the descriptions of the pump assemblies 203, 303, 403, 503are incorporated by reference into one another in their entireties.Additionally, the description of the common subject matter generally maynot be repeated here.

The pump assembly 603 may include a cover 617, and a pump including apump body 623 having a hub 625 and defining a rotor pocket 627, a driverotor 629 disposed about the hub 625, and a driven rotor 631 disposed inthe rotor pocket 627. The drive rotor 629 is disposed at an upper end ofthe pump body 623 between the center support 637 and the pump body 623.The pump assembly 603 may also include a drive coupling 633 coupled tothe drive rotor 629, a shaft 635 connected to the drive coupling 633, acenter support 637 and a bearing 639 carried by the center support 637to support the shaft 635 extending therethrough, and a driven member 641of a magnetic coupling coupled to the shaft 635. The pump assembly 603may further include a case (not shown).

The cover 617 may be injection molded from an acetal resin and mayinclude a flat face to cooperate with a lower end of the stationary pumpbody, and a pocket in the flat face to accommodate an end of the shaft635.

An inner diameter of the drive rotor 629 is piloted for rotation on ahub 625 of the body 623, and an outer diameter of the driven rotor 631is supported for rotation within the rotor pocket 627 of the body 623.

The drive coupling 633 may include an integral thrust bearing member orhub 634, a flange 636 extending transversely from the hub 634, and drivedogs 649 extending longitudinally from the flange 636 that extend intocorresponding pockets or blind bores 649′ in the drive rotor 629. Thehub 634 is engageable with the bearing 639 to axially support the shaft635 and protect the pump against axial forces on the shaft 635 inducedby the magnetic attractive forces on the driven member 641. The drivecoupling 633 may include an internal diameter splined for coupling tothe shaft 635, or may be press fit to a corresponding knurled portion ofthe shaft 635, or otherwise fixed to the shaft 635.

The shaft 635 may be of substantially solid cylindrical shape andincludes one or more bearing diameters supported by the pump body 623and/or the center support 637.

The center support 637 may be of any suitable construction andcomposition and, for example, may include an outer wall 653 that may begenerally cylindrical, and a wall 655 extending generally transverselyfrom the outer wall 653 and including a stepped hub 657 defining a drivecoupling pocket to accept the drive coupling 633 therein and a bearingpocket to accept the bearing 639 therein. The bearing 639 may extendlongitudinally into the drive coupling pocket wherein a lower end of thebearing 639 may be configured for contact with the rotating drivecoupling 633. As such, the bearing may function as both a radial bushingand thrust bearing. The bearing 639 may be composed of carbon, PPS orany other suitable material.

As shown in FIGS. 8 and 9, a reactant delivery module 700 may be carriedother than by the top or an upper wall of a storage tank 702. In thisexample, the reactant delivery module 700 is constructed and arranged tobe carried by or mounted to a lower wall 704 of the storage tank 702.The module 700 may include, among other things, a mounting flange 706, areactant delivery device 708, and a pressure regulator 710.

The reactant delivery device 708, or pressurizing device, may be anysuitable device capable of moving a desired amount or rate of thereactant from the storage tank and may include, but is not limited to,the various devices set forth herein. In that regard, the device 708 mayinclude a pump that may be magnetically driven with a motor separatedfrom but magnetically communicated with the pump.

The pressure regulator 710 may likewise be any suitable device tocontrol the pressure of fluid discharged from the storage tank 702. Asshown in FIGS. 8 and 9, the pressure regulator 710 may be a flow-throughtype regulator having a pressure regulating valve (not shown) disposedbetween an inlet, outlet and a bypass outlet. Fluid discharged from thepump enters the inlet of the regulator 710 and fluid at or below athreshold pressure passes through the regulator 710 and out of theoutlet for delivery through the flange 706 and from the storage tank702. Fluid above the threshold pressure is discharged through the bypasspassage and back into the storage tank 702. The bypass passage maycommunicate with the conduit 112, as set forth above. A representativefuel pressure regulator 710 is disclosed in U.S. Pat. No. 5,265,644, thedisclosure of which is incorporated herein by reference in its entirety.Of course, other pressure regulating or pressure relief devices may beused.

The mounting flange 706 may include an inner surface 711 at leastpartially exposed to the interior of the storage tank 702, an outersurface 712 opposite the inner surface 711 and outside of the storagetank, and an outlet 714 (FIG. 9) passing through the flange 706 topermit fluid flow out of the storage tank through the flange. Themounting flange 706 may further include one or more sealing surfacesadapted to be sealingly coupled to the storage tank. The sealingsurfaces may include a radially outwardly extending rim 716 adapted tooverlie and be sealed to an outside surface 718 of the storage tank wall704, and/or an axially extending and circumferentially continuous wall720 that may be spaced radially inwardly from the outer periphery of therim 716 and adapted to be received within and/or sealed to an opening inthe storage tank 702. To hold the reactant delivery device 708 andpressure regulator 710 in desired positions relative to the flange 706and within the storage tank 702, the flange 706 may include retentionfeatures for one or both of these devices.

The retention feature for the reactant delivery device 708 may be formedor carried on the flange 706, or it may be separate from the flange. Theretention feature may include one or more cavities, fasteners, rods,skirts, flanges or other features on or to which the reactant deliverydevice 708 may be coupled or carried. In the implementation shown, theretention feature includes one or more generally cylindrical cavities722 (FIG. 8) in which portions of the reactant delivery device 708 arecarried. The cavities may be defined by one or more skirts orcylindrical walls 724 extending from one or both of the inner and outersurfaces 710, 712 of the flange 706. A dividing wall may separate amotor portion of the cavity 722 from a pump portion of the cavity 722yet permit magnetic communication between them as previously set forthherein. The dividing wall may be formed in one-piece with the flange706, or formed separately therefrom, and disposed within the cavity 722.The cavity 722 may be open at both ends to permit insertion of thecomponents of the reactant delivery device 708 from each end of thecavity 722. The reactant delivery device 708 may be received partiallyor entirely within the cavity 722 and retained therein by an end cap732. To this end, the wall 724 may have various retention features, suchas angled tabs 734, that are received in complementary slots or openings736 in the end cap 732 that permit snap-fit retention of the end cap 732on the wall 724 to retain the reactant delivery device 708 within thecavity 722.

The retention feature for the pressure regulator 710 may include aprojecting wall 738 which may be tubular and define an internal cavityor passage through which fluid may flow. The cavity or passage may leadto the flange outlet 714 so that pressurized fluid that flows out of thepressure regulator 710 outlet flows through the flange outlet 714 fordelivery downstream of the storage tank 702. All or a portion of thepressure regulator 710 may be disposed within the cavity or passagedefined by the wall 738, or the regulator 710 may be simply carried byor coupled to the wall 738.

In the implementation shown, the end cap 732 that retains the reactantdelivery device 708 may include an inlet 742 (FIG. 8) that is coupled toa filter 744 to provide a filtered supply of fluid (in this example, thefluid is the reactant) to the pump, such as through an inlet tube 746extending between the filter 744 and inlet 742. Of course, the filter744 could be carried by the end cap 732 without any intermediate tube746. The end cap 732 may also include or define an outlet 748 throughwhich fluid discharged from the reactant delivery device 708 flows.

The pressure regulator 710 may be carried by a housing 750 that may becoupled to the end cap 732. The housing 750 may include a cavity (notshown) in which the pressure regulator 710 is received and a clip 752may be used to retain the pressure regulator 710 within the cavity. Aninlet 754 of the housing 750 may be communicated with the pressureregulator inlet, an outlet 756 of the housing 750 may be communicatedwith the pressure regulator outlet, and one or more bypass outlets 758,759 (two are shown in the illustrated embodiment) of the housing 750 maybe communicated with the bypass outlet of the pressure regulator 710. Inthis way, the flow of bypassed fluid could be bifurcated to provide twoor more separate streams of bypassed fluid which may be routed todifferent areas of the storage tank 702, if desired, to improvedistributed melting of the reactant. The outlet 756 of the housing 750may be arranged to be sealingly connected to the flange wall 738 toprovide fluid flow from the pressure regulator outlet to the flangeoutlet 714 for delivery from the storage tank 702.

In the implementation shown, the outlet 748 of the end cap 732 iscoupled to the inlet 754 of the housing 750 which leads to the inlet ofthe pressure regulator 710 to provide pressurized fluid from thereactant delivery device 708 to the inlet of the pressure regulator 710.The housing 750 and end cap 732 may be formed in one-piece such as byinjection molding or other process. This may enable separate fluid linesbetween the pressurizing device 708 and pressure regulator 710 to beeliminated, which also eliminates the need to ensure sealed connectionsof such fluid lines.

As discussed above, one or more heaters may be provided to melt frozenreactant within the storage tank 702. In one implementation, the heatermay include forming the flange 706 out of a metallic material andapplying electrical energy to or otherwise heating the flange 706. Withthe flange 706 disposed at or near the bottom of the storage tank 702,reactant will be in contact with the flange 706, and when frozen, willbe melted by the heated flange. To improve the flange heating, an ormore than one electrically conductive coating 760 (FIG. 10) may beapplied to the outside surface 712 of the flange 706, and an electricalconnection may be coupled to the coating 760 to provide electricity tothe coating and flange 706. The coating may be applied and/or cover allor less than all of the outer surface 712 of the flange 706. Theelectrical connection may be any suitable means or device to apply powerto the flange and/or its coating(s). For example, the electricalconnection may be a connector to which wires 762 are connected, or theelectrical connection may include connecting the wires 762 (e.g. bysoldering) directly to the flange and/or its coatings without anyseparate connector. The coating 760 may be applied as a liquid, sheet,foil, or in any other suitable form. In one form, the coating 760 may bea metallic ink that is sprayed or otherwise applied to the flange andallowed to dry or cure so that it is adhered or bonded to the flange. Awide range of materials may be used as the coating. A second coating 764(FIG. 10), which may be a potting material, may be applied over thefirst coating 760 to protect the first coating and insulate the flangeand coating(s) 760.

Electrical power may be applied to the flange 706 and/or coating 760 ina controlled manner to provide a desired temperature or temperatureincrease of the flange 706. In one implementation, between about 100 to150 watts may be applied to the flange 706 and/or coating 760. A wattdensity of between about 0.1 to 1 watt/mm² across the surface of theflange 706 may be desirable in at least certain applications. Too highof a watt density may melt the reactant from the bottom of the storagetank 702 toward the top in a relatively straight, vertical patternwithout much sideways dispersion of the melting (e.g. like a cylinder).Too low of a heat density may not sufficiently melt the reactant, maycause too much sideways dispersion of the melt pattern and not enoughmelting progress vertically (e.g. toward an upper wall of the storagetank) in the frozen reactant. As noted above with regard to otherimplementations of the heater, the surface temperature of the flange 706in at least some implementations may be controlled to not exceed about80° C., although other temperature thresholds or ranges could be used asdesired.

The temperature of the flange 706 may be controlled by use of athermister 766 (FIG. 8), and a representative thermister 766 is carriedby a clip 768 in the area of the filter 744 and flange 706.Additionally, a low reactant level sensor 770 may be provided at adesired height or level in the area of the bottom of the storage tank702, and is shown as being carried by the clip 768 and part of a unitwith the thermister 766. The low level sensor 770 may include spacedapart electrical leads that are electrically coupled together when bothare in contact with an electrically conductive fluid, like urea. In theabsence of the fluid contacting both leads, the sensor 770 provides asignal indicative that there is a low level of reactant within thestorage tank 702. Wires 771 for the thermister 766 and level sensor 770may be provided through a conduit 772 that may be sealingly received ona fitting 774 to provide a sealed connection of the wires within thestorage tank 702. The conduit 772 may extend to a similar fitting 776(FIG. 9) on the flange 706 to permit the wires 771 to pass through theflange 706 and out of the storage tank 702.

While the forms of the invention herein disclosed constitute presentlypreferred embodiments, many others are possible. It is not intendedherein to mention all the possible equivalent forms or ramifications ofthe invention. It is understood that the terms used herein are merelydescriptive, rather than limiting, and that various changes may be madewithout departing from the spirit or scope of the invention.

What is claimed is:
 1. A reactant delivery module for a reactantdelivery system having a storage tank in which a supply of reactant ismaintained, comprising: a mounting flange adjacent the bottom of thestorage tank, formed of a thermally conductive material, having asealing surface adapted to be coupled to the storage tank andconstructed to be in heat transfer relationship with reactant adjacentthe bottom of the storage tank and within the storage tank; a reactantdelivery device carried by the mounting flange and within the storagetank; and an electrically conductive coating applied to the flange andan electrical connection coupled to the coating to increase thetemperature of the reactant when electric power is applied to thecoating.
 2. The module of claim 1 wherein a watt density of betweenabout 0.1 to 1 watt/mm² is provided across the surface of the flange. 3.The module of claim 1 wherein the mounting flange is adapted to becoupled to a bottom wall of the storage tank and to be in direct contactwith reactant stored within the storage tank.
 4. The module of claim 1which also includes a housing coupled to the mounting flange to retainat least a portion of the reactant delivery device, and a pressureregulator within the storage tank and carried by the housing in fluidcommunication with an outlet of the reactant delivery device.
 5. Themodule of claim 4 wherein the pressure regulator includes an outlet thatis open to an interior surface of the flange, where the interior surfaceof the flange is adapted to be disposed in contact with reactant in thestorage tank so that the pressure regulator outlet is oriented todischarge reactant into the storage tank.
 6. The reactant deliverysystem of claim 1 including a filter connected to the pumping device anda plurality of heaters distributed within the tank at least partiallyaround the pumping device and filter, and including heating elementsencapsulated in phase-change material that is separate from thereactant.
 7. A reactant delivery system for engine exhaust gastreatment, comprising: a tank in which a reactant is received; a pumpingdevice having an inlet disposed within the interior of the tank toreceive the reactant, and an outlet through which the reactant isdischarged; a pressure relief device having an inlet in fluidcommunication with the outlet of the pumping device, a primary outlet todischarge the reactant under pressure to a downstream location, and abypass outlet through which at least some of the reactant dischargedfrom the pumping device is selectively discharged; a reactantdistribution device in fluid communication with the bypass outlet of thepressure relief device and having a conduit arranged in a non-linearfashion within the tank with at least two apertures oriented indifferent directions within the tank to distribute the reactant to atleast two different locations within the tank; and the total flow areathrough the apertures for a given length of the conduit increases as thedistance from the pressure relief device increases to achieve relativelyconsistent flow delivered by the conduit along its length.
 8. The systemof claim 7 wherein the pressure relief device permits flow through thebypass outlet of the reactant when the pressure of the reactant at thepressure relief device is above a threshold.
 9. The system of claim 7wherein the conduit is flexible and includes at least three aperturesspaced apart along its length.
 10. The system of claim 9 wherein theapertures are positioned and directed so as to selectively distributeliquid reactant in three planes.
 11. The system of claim 10 wherein atleast one of the apertures is located in the area of the pumping deviceto distribute liquid reactant in the area of the pumping device.
 12. Thesystem of claim 7 including a plurality of heaters distributed withinthe tank at least partially around the pumping device and includingheating elements encapsulated in phase-change material that is separatefrom the reactant.